Oil well hoist



W. S. CRAKE OIL WELL HOIST May 11, 1954 Filed June 23, 1951 7L1 IL PIC-3.2

INVENTOR WLFRiD S. CRAKE- His ATTORNEY Patented May 11 1954 OIL WELL HOIST Wilfred S. Crake, Houston, Tex., assignor to Shell Development Company, Emeryville, Calif., a

corporation of Delaware Application June 23, 1951, Serial No. 233,217

1 Claim.

This invention relates to well drilling equipment and pertains more particularly to cable hoisting apparatus for use with a lightweight drill rig.

In recent times, it has been necessary to drill deeper and deeper into the earth in order to find suificient quantities of oil. As the depth of wells has increased, the size and weight of the well drilling equipment used to drill these wells has also increased. The use of larger and heavier well drilling equipment is accompanied by increased costs, difficulties in transportation, accelerated rate of wear of the equipment, etc.

As drilling equipment is hoisted by a drawworks within a drill derrick, cable is removed from the fall lines of the hoisting system and wound on the hoist drum of the drawworks. While the first portion of cable to be stored on the drum is wound directly on the cylindrical face of the drum, subsequent lengths of cable which are put on the drum over-lie the layer of cable already on the drum and form additional layers of cable, one on top of each other. Because of the heavy weight of the drilling equipment being hoisted, the cable running to the hoist drum is under a high tension which causes the cable to crush and damage or wear the cable already stored on the drum.

It is therefore a primary object of this invention to provide an oilwell hoist in which the excess cable is subjected only to low tension as it is reeled onto the storage drum.

Another object of this invention is to provide an oilwell hoist wherein the hoisting cable. is wound under high stress on the main pulling drum or drums in a single layer only.

Another object of the present invention is to provide an oilwell hoist wherein the hoisting cable may be readily wound on the storage drum in layers with a minimum of wear and crushing action.

A further object of this invention is to provide an oilwell hoist having cable take-up means incorporated therein for maintaining a constant tension on the hoist cable as it is wound on a storage drum.

Additional objects and advantages will become more apparent from a study of the following detailed description when considered in conjunction with the accompanying drawing wherein:

Figure 1 is a diagrammatic view of a well drilling derrick with a preferred form of an oilwell hoist and hoisting system according to the present invention.

Figure 2 is a view in top elevation ofpart of the hoisting mechanism shown in Figure 1.

Referring to Figure 1 of the drawing, the oilwell hoist of the present invention is illustrated as being positioned adjacent a drilling derrick'll equipped with a crown block 12, traveling block and hook assembly l3, and a hoisting cable [4 having its dead end I5 anchored in a suitable manner, such as for example, to an anchoring member 46 at the base of the derrick.

The hoist mechanism of the present invention comprises a storage or spooling drum 11, one or more. suitable prime mover means or drive motors It, a pair of driving or pulling drums l8 and 20 and a suitable cable take-up device which in this case comprises a pair of stationary blocks 21 and 22 and a traveling block 24 supported on a member projecting from the main rig or suitable frame 23 at a predetermined height above the drums l1, l9 and '20. The live end of the cable I 4 coming from the crown block l2 goes down to the driving drums I9 and 20 where it is wound or wrapped over the two drums in an over-and-over manner, each wrap or loop extending over both drums and lying alongside the other wraps in such a manner as to form only one layer of cable over the drums. Preferably, the outer surfaces of drums I9 and 20 are grooved to prevent lateral slippage of the cable thereon. From drum 20 the cable I4 passes up through frame 23, over block 2|, down through traveling block 24, thence over block 22 and down to drum I! where its live end is secured.

AS shown in Figure 2, the driving drums l9 and 2|) are mounted on shafts 25 and 26 in parallel spaced relationship with each other with the cylindrical surfaces of the drums adjacent. The drums l9 and 2B are mechanically linked together by a chain drive 21 so that the drums are driven in unison. Drum I1 is also locked in rotation to drum 20 by a chain drive '28. The prime movers l8 may be connected by suitable transmission means to drive drums l9 and 20 but are preferably connected by chain drives 29 and 30 to a two-speed countershaft 3| which may be alternately connected, through chain drive 32 and clutch 33 or by chain drive 34 and clutch 35, to drive the drum 20 and thence drums I! and I9.

Either of the cable drums ll, l9 and 2D, or any combination of these drums may be equipped with conventional braking means well known in the art of well drilling equipment. Thus, it may be seen that the present oilwell hoist may be equipped with three times the mechanical braking power as compared with a hoist system employing a singlehoisting drum. If desired, an auxiliary brake 36 (Figure 2), such as a dynamic brake, may be coupled to one of the drums (for example, drum l9) by a drive chain 31 and clutch 38. Additionally, an auxiliary motor 39 may be provided for driving the storage drum IT to reel the entire cable on said drum when the derrick and hoist are being dismantled for transportation to another location. To facilitate the moving of the present oilwell hoist from one location to another, the various elements of the hoist may be fixedly secured to a movable platform 49 (Figure 1).

In operation, as the driving drums i9 and 20 are rotated counterclockwise, the traveling block i3 is raised and the cable 54 is pulled through the hoist system and wound onto the storage drum I? under low tension. A weight 42 of predetermined value is secured to traveling block 24.

for maintaining a constant low tension in the cable [4 as it leaves drum 20 and goes over pulleys 2| and 22 and onto drum ll. This small tension on the cable provides suificient friction between the cable 14 and drums l9 and 26 to prevent slippage. Thus, a light pull on the cable l4. between drums 2G and ll, or a slight braking action applied to drums id or "it is sufiicient to counterbalance a heavy load, said load being equal to the number of wraps or loops of cable around the drums l8 and 2f! times the friction force per wrap on the cable i4 rising from drum is to crown block i2. This friction can be controlled at a desired value by proper selection of the number of wraps of the cable is, by the size of the weight 42 employed, and/or the amount of braking force applied to drum I9 or 21].

It will beseenthat as the cable 54 is removed from the fall lines of the hoist system and wound on storage drum H, the diameter of the drum spool is increased each time a complete layer of cable has been wound thereon. As the diameter of the drum il increases, the increased length of cable taken up per revolution of the drum I7 is taken out of the fall lines to traveling block 24 causing. the latter to rise a distance equal to onehalf this increased. cable length, or a distance proportional thereto if block 24 contains more than one pulley or in the event a different block system is employed.

For example, if drums ll, 19 and 20 are all of the same diameter, the traveling block 24 will not rise or. fall as the first layer of cable I4 is wound on the drum H but will begin to rise thereafter. If drum ll has a 24-inch diameter and. accommodates 32 turns of one-inch cable per layer, the first three layers Will contain about 201, 218 and 235 feet of cable respectively. Thus, when the second and third layers of one-inch cable are reeled on the drum ll, the diameter of the drum on which the cable is reeled increases by about 2 inches for each additional layer, causing each additional layer on the drum to contain about 17 feet more of cable than the preceding layer. Since these extra'lengths of cable are removed from the fall lines to block 24, the block 24 together with weight 42 is caused to rise about 8 /2 feet while the second layer of cable is being wound on the drum and another 8 feet when the third layer of cable is added.

From the above figures it may be seen that three layers of one-inch cable wound on drum ll would be about 650 feet lon When this cable is unwound from the drum, 34 feet of it would-be added to the fall lines to block 24 while the remainder would be added in the fall lines to block l3- If the fall lines to block 13 contained six strands, the block 13 could 'be raised and lowered a height of about feet while block 24 was raised and lowered 17 feet. Preferably, a multiple fall line system is used to traveling block 24 thus permitting a lower frame member 23 to be used. For example, the weight 42 and traveling block 24 would be raised or lowered only about 8 feet if the fall lines had 4 strands.

Using the system of fall lines to blocks I3 and 24 illustrated in Figure l, the vertical movement of the weight 42 and block 24 can be further reduced by employing a drum I! having a diameter which is slightly smaller, say 2 inches, than the diameter of drums l9 and 2%). For example, if drums i9 and 23 have 24-inch diameters, drum if has a 22-inch diameter, and one-inch cable is used, more cable (201 feet) will be removed from the fall lines to block I3 than is reeled on drum i "i (184 feet) due to the latters smaller diameter. The difference will be taken up by the fall lines to block 25 causing weight 42 to drop 8 /2 feet. With one layer of cable on the drum H, all three drums ll, I9 and 28) now have the same diameter and no change in position of weight 42 occurs when the second layer (201 feet) of cable is reeled on the drum it. But the diameter of the drum with two layers of cable added is now greater than the diameter of drums i9 and 20 so that when a third layer of cable is put on the drum ll the cable will be reeled thereon at a ratefaster than it is removed from the fall lines to block I3 causing the block to rise 8 /2 feet. Thus, by using a reeling drum ll having a slightly smaller diameter than drums l9 and 20, weight 42 is caused to fall and then rise 8 /2 feet rather than rise 17 feet as it did in the first example. From the above it may be seen that by selecting drums l7, l9 and 2d of proper diameters, the rise and fall of weight 42 can be minimized and the height of frame 23 reduced. Further reduction in the height of the frame 23' may be realized by employing multiple fall lines to traveling block 24 and by increasing weight 42 in proportion to this number of fall lines so that tension on therope at drums IT and 20 remains constant.

From the above description it may be seen that a hoisting system has been provided wherein cable, as it is being continuously removed from the fall lines of the system, is wound at high tension onto the driving drums l9 and 20 in a single layer thus obviating any crushing action of cable being wound on cable. At the same time other portions of the hoisting cable are being removed from the driving drums and the storage drum by a cable take-up assembly. Due to the short distance of travel needed by the Weight 42 of the take-up assembly, it may be seen that the. frame 23 of the assembly may be relatively low and of lightweight construction which may readily be dismantled and moved when the oilwell hoist is moved to another location. 7

I claim as my invention:

A hoisting apparatus for use with well drilling equipment comprising a drill rig, a crown block, a traveling block, a hoisting cable forming fall lines between said crown and traveling blocks, a pair of driving hoist drums on which the cable is wound in a plurality of turns forming a single layer, each turn encompassing both drums, a, storage drum from which said cable. is unreeled as it is passed to the hoist drums, link means rigidly connecting all of said drums for synchronized rotation, and cable supply and take-up means between said hoist drums and said storage drum for selectively introducing and removing additional cable to maintain a constanttension on the cable operatively connected between said drums, said cable supply and take-up means comprising a support frame secured to the derrick and extending therefrom above said hoist and storage drums, a multiple fall-line pulley system depending from said support frame, said pulley system including at least one crown block aflixed to said frame and a Weighted traveling block suspended therefrom on multiple fall lines of the cable, said cable being unwound from said storage drum into said fall lines of said pulley system and thence out of said fall lines and onto said hoist drums, said cable in said fall lines being of a length just suificient to compensate for changes in the length of the cable moving between said hoist drums and said storage drum due to changes in the diameter of said storage drum as cable is reeled thereon and removed 5 therefrom.

References Cited in the file of this patent UNITED STATES PATENTS 

